Seeking to capture the fan/collectors/enthusiast gene, "The Big Year" uses Mark Obmascik's book about obsessed "birders" and transforms it into a genial if slow-moving, almost sleepy comedy.

Seeking to capture the fan/collectors/enthusiast gene, “The Big Year” uses Mark Obmascik’s book about obsessed “birders” and transforms it into a genial if slow-moving, almost sleepy comedy. Steve Martin, Jack Black and Owen Wilson play the central trio — each at different stages of lives they put on hold to pursue their shared passion — in a contest to eclipse what amounts to the Babe Ruth home run record of bird watching. Director David Frankel’s pic delivers sweet and (more rarely) amusing moments, but this odd duck never completely gets off the ground, and box office ought to mirror that flight path.

Loosely inspired by Obmascik’s chronicle of three men vying to top each other during “the Big Year” competition in 1998, Frankel (“The Devil Wears Prada” and “Marley & Me,” reunited here with Wilson) and screenwriter Howard Franklin loosely start with that template as a foundation to explore what’s really important — the ways people and their loved ones accommodate activities that become all-consuming.

“You can’t compare golf to this. Golf is like a hobby,” explains Wilson’s Kenny Bostick to his frustrated wife (Rosamund Pike), later trying to rationalize missed events and blown deadlines by saying, “This is what I’m great at.”

Indeed, Bostick holds the birder record, having sighted 732 North American birds in a single “big year,” which beckons to his two principal competitors: Stu Preissler (Martin), a rich businessman whose wife (JoBeth Williams) is more resigned to his yearlong flight of fancy than are his harried subordinates, who keep pleading with him to put out fires at work; and Brad Harris (Black), a divorced 36-year-old computer programmer who gets a mixed reaction to his obsession from his adoring, supportive mom (Dianne Wiest) and gruff dad (Brian Dennehy).

Given Kenny’s ruthlessly competitive nature, Stu and Brad (who doubles as the narrator) strike up an unlikely friendship. Mostly, though, the protagonists’ paths intersect fitfully as they crisscross the continent responding to weather and seasonal patterns that will theoretically help them pad their totals.

Beyond the leads, Frankel and company have aided their cause immeasurably by casting the movie to the hilt, with accomplished actors like Rashida Jones, Tim Blake Nelson, Anjelica Huston and Jim Parsons in what amount to minimal “there are worse ways to spend your TV hiatus” roles. Pic also makes appropriate use of various avian-related songs, including “Surfin’ Bird” as Brad’s ringtone.

That said, the story unfolds slowly, and the running tally of bird sightings and calendar dates popping up onscreen only provide a frequent reminder of the laborious march until Dec. 31, when the competition ends. Nor does “Big Year” completely work as a travelogue, despite destinations that range from a remote Alaskan island to the Everglades. Like the central characters, the narrative can’t see the forest, as it were, for the birds.

For all that, there are some welcome aspects to the production, including a lack of big slapstick elements. Yet by eschewing broad, easy laughs, Frankel only reinforces a sense of this being less a bigscreen comedy than an inordinately well-cast Hallmark movie. Admittedly, there ought to be room for this sort of unassuming exercise movie in the theatrical space, but given the shifting winds, a project like that has to be almost pitch-perfect to stick the landing. As is, “The Big Year” is pleasant enough, but finally suffers — pardon the analogy — from being neither fish nor fowl.